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autofs4: Fix wait validation 

It is possible for the check in wait.c:validate_request() to return
an incorrect result if the dentry that was mounted upon has changed
during the callback.

Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Ian Kent 2011-01-14 18:46:30 +00:00 committed by Al Viro
parent 6651149371
commit 9e3fea16ba
1 changed files with 16 additions and 1 deletions
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17
fs/autofs4/waitq.c
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@ -309,6 +309,9 @@ static int validate_request(struct autofs_wait_queue **wait,
* completed while we waited on the mutex ...
*/
if (notify == NFY_MOUNT) {
struct dentry *new = NULL;
int valid = 1;
/*
* If the dentry was successfully mounted while we slept
* on the wait queue mutex we can return success. If it
@ -316,8 +319,20 @@ static int validate_request(struct autofs_wait_queue **wait,
* a multi-mount with no mount at it's base) we can
* continue on and create a new request.
*/
if (!IS_ROOT(dentry)) {
if (dentry->d_inode && d_unhashed(dentry)) {
struct dentry *parent = dentry->d_parent;
new = d_lookup(parent, &dentry->d_name);
if (new)
dentry = new;
}
}
if (have_submounts(dentry))
return 0;
valid = 0;
if (new)
dput(new);
return valid;
}
return 1;